DESCRIPTION

STOP! If you're just getting started writing tests, have a look at
Test::Simple first. This is a drop in replacement for Test::Simple
which you can switch to once you get the hang of basic testing.

The purpose of this module is to provide a wide range of testing
utilities. Various ways to say "ok" with better diagnostics,
facilities to skip tests, test future features and compare complicated
data structures. While you can do almost anything with a simple
ok()
function, it doesn't provide good diagnostic output.

I love it when a plan comes together

Before anything else, you need a testing plan. This basically declares
how many tests your script is going to run to protect against premature
failure.

The preferred way to do this is to declare a plan when you useTest::More
.

If you don't know how many tests you're going to run, you can issue
the plan when you're done running tests.

$number_of_tests is the same as plan(), it's the number of tests you
expected to run. You can omit this, in which case the number of tests
you ran doesn't matter, just the fact that your tests ran to
conclusion.

This is safer than and replaces the "no_plan" plan.

Test names

By convention, each test is assigned a number in order. This is
largely done automatically for you. However, it's often very useful to
assign a name to each test. Which would you rather see:

ok 4

not ok 5

ok 6

or

ok4 - basicmulti-variable

not ok5 - simpleexponential

ok6 - force == mass * acceleration

The later gives you some idea of what failed. It also makes it easier
to find the test in your script, simply search for "simple
exponential".

All test functions take a name argument. It's optional, but highly
suggested that you use it.

I'm ok, you're not ok.

The basic purpose of this module is to print out either "ok #" or "not
ok #" depending on if a given test succeeded or failed. Everything
else is just gravy.

All of the following print "ok" or "not ok" depending on if the test
succeeded or failed. They all also return true or false,
respectively.

ok

ok($got eq $expected,$test_name);

This simply evaluates any expression ($got eq $expected
is just a
simple example) and uses that to determine if the test succeeded or
failed. A true expression passes, a false one fails. Very simple.

$test_name is a very short description of the test that will be printed
out. It makes it very easy to find a test in your script when it fails
and gives others an idea of your intentions. $test_name is optional,
but we very strongly encourage its use.

Should an ok() fail, it will produce some diagnostics:

not ok18 - sufficientmucus

# Failed test 'sufficient mucus'

# in foo.t at line 42.

This is the same as Test::Simple's ok() routine.

is

isnt

is($got,$expected,$test_name);

isnt($got,$expected,$test_name);

Similar to ok(), is() and isnt() compare their two arguments
with eq
and ne
respectively and use the result of that to
determine if the test succeeded or failed. So these:

# Is the ultimate answer 42?

is(ultimate_answer(),42,"Meaning of Life");

# $foo isn't empty

isnt($foo,'',"Got some foo");

are similar to these:

ok(ultimate_answer() eq 42,"Meaning of Life");

ok($foo ne '',"Got some foo");

(Mnemonic: "This is that." "This isn't that.")

So why use these? They produce better diagnostics on failure. ok()
cannot know what you are testing for (beyond the name), but is() and
isnt() know what the test was and why it failed. For example this
test:

The second argument is a regular expression. It may be given as a
regex reference (i.e. qr//) or (for better compatibility with older
perls) as a string that looks like a regex (alternative delimiters are
currently not supported):

like($got,'/expected/','this is like that');

Regex options may be placed on the end ('/expected/i'
).

Its advantages over ok() are similar to that of is() and isnt(). Better
diagnostics on failure.

unlike

unlike($got,qr/expected/,$test_name);

Works exactly as like(), only it checks if $got does not match the
given pattern.

cmp_ok

cmp_ok($got,$op,$expected,$test_name);

Halfway between ok() and is() lies cmp_ok(). This allows you to
compare two arguments using any binary perl operator.

# ok( $got eq $expected );

cmp_ok($got,'eq',$expected,'this eq that');

# ok( $got == $expected );

cmp_ok($got,'==',$expected,'this == that');

# ok( $got && $expected );

cmp_ok($got,'&&',$expected,'this && that');

...etc...

Its advantage over ok() is when the test fails you'll know what $got
and $expected were:

not ok1

# Failed test in foo.t at line 12.

# '23'

# &&

# undef

It's also useful in those cases where you are comparing numbers and
is()'s use of eq
will interfere:

This function only works on new() and it assumes new() will return
just a single object which isa $class
.

pass

fail

pass($test_name);

fail($test_name);

Sometimes you just want to say that the tests have passed. Usually
the case is you've got some complicated condition that is difficult to
wedge into an ok(). In this case, you can simply use pass() (to
declare the test ok) or fail (for not ok). They are synonyms for
ok(1) and ok(0).

Use these very, very, very sparingly.

Module tests

You usually want to test if the module you're testing loads ok, rather
than just vomiting if its load fails. For such purposes we have
use_ok
and require_ok
.

use_ok

BEGIN {use_ok($module);}

BEGIN {use_ok($module,@imports);}

These simply use the given $module and test to make sure the load
happened ok. It's recommended that you run use_ok() inside a BEGIN
block so its functions are exported at compile-time and prototypes are
properly honored.

Complex data structures

Not everything is a simple eq check or regex. There are times you
need to see if two data structures are equivalent. For these
instances Test::More provides a handful of useful functions.

NOTE I'm not quite sure what will happen with filehandles.

is_deeply

is_deeply($got,$expected,$test_name);

Similar to is(), except that if $got and $expected are references, it
does a deep comparison walking each data structure to see if they are
equivalent. If the two structures are different, it will display the
place where they start differing.

is_deeply() compares the dereferenced values of references, the
references themselves (except for their type) are ignored. This means
aspects such as blessing and ties are not considered "different".

is_deeply() currently has very limited handling of function reference
and globs. It merely checks if they have the same referent. This may
improve in the future.

Diagnostics

If you pick the right test function, you'll usually get a good idea of
what went wrong when it failed. But sometimes it doesn't work out
that way. So here we have ways for you to write your own diagnostic
messages which are safer than just printSTDERR
.

diag

diag(@diagnostic_message);

Prints a diagnostic message which is guaranteed not to interfere with
test output. Like print @diagnostic_message is simply concatenated
together.

Will dump the contents of any references in a human readable format.
Usually you want to pass this into note
or diag
.

Handy for things like...

is_deeply($have,$want) || diagexplain$have;

or

noteexplain \%args;

Some::Class->method(%args);

Conditional tests

Sometimes running a test under certain conditions will cause the
test script to die. A certain function or method isn't implemented
(such as fork() on MacOS), some resource isn't available (like a
net connection) or a module isn't available. In these cases it's
necessary to skip tests, or declare that they are supposed to fail
but will work in the future (a todo test).

For more details on the mechanics of skip and todo tests see
Test::Harness.

The way Test::More handles this is with a named block. Basically, a
block of tests which can be skipped over or made todo. It's best if I
just show you...

SKIP: BLOCK

SKIP:{

skip$why,$how_many if $condition;

...normaltestingcodegoeshere...

}

This declares a block of tests that might be skipped, $how_many tests
there are, $why and under what $condition to skip them. An example is
the easiest way to illustrate:

If the user does not have HTML::Lint installed, the whole block of
code won't be run at all. Test::More will output special ok's
which Test::Harness interprets as skipped, but passing, tests.

It's important that $how_many accurately reflects the number of tests
in the SKIP block so the # of tests run will match up with your plan.
If your plan is no_plan
$how_many is optional and will default to 1.

It's perfectly safe to nest SKIP blocks. Each SKIP block must have
the label SKIP
, or Test::More can't work its magic.

You don't skip tests which are failing because there's a bug in your
program, or for which you don't yet have code written. For that you
use TODO. Read on.

With a todo block, the tests inside are expected to fail. Test::More
will run the tests normally, but print out special flags indicating
they are "todo". Test::Harness will interpret failures as being ok.
Should anything succeed, it will report it as an unexpected success.
You then know the thing you had todo is done and can remove the
TODO flag.

The nice part about todo tests, as opposed to simply commenting out a
block of tests, is it's like having a programmatic todo list. You know
how much work is left to be done, you're aware of what bugs there are,
and you'll know immediately when they're fixed.

Once a todo test starts succeeding, simply move it outside the block.
When the block is empty, delete it.

NOTE: TODO tests require a Test::Harness upgrade else it will
treat it as a normal failure. See "CAVEATS and NOTES").

todo_skip

TODO:{

todo_skip$why,$how_many if $condition;

...normaltestingcode...

}

With todo tests, it's best to have the tests actually run. That way
you'll know when they start passing. Sometimes this isn't possible.
Often a failing test will cause the whole program to die or hang, even
inside an evalBLOCK
with and using alarm. In these extreme
cases you have no choice but to skip over the broken tests entirely.

The syntax and behavior is similar to a SKIP:BLOCK
except the
tests will be marked as failing but todo. Test::Harness will
interpret them as passing.

When do I use SKIP vs. TODO?

If it's something the user might not be able to do, use SKIP.
This includes optional modules that aren't installed, running under
an OS that doesn't have some feature (like fork() or symlinks), or maybe
you need an Internet connection and one isn't available.

If it's something the programmer hasn't done yet, use TODO. This
is for any code you haven't written yet, or bugs you have yet to fix,
but want to put tests in your testing script (always a good idea).

Test control

BAIL_OUT

BAIL_OUT($reason);

Indicates to the harness that things are going so badly all testing
should terminate. This includes the running any additional test scripts.

This is typically used when testing cannot continue such as a critical
module failing to compile or a necessary external utility not being
available such as a database connection failing.

Discouraged comparison functions

The use of the following functions is discouraged as they are not
actually testing functions and produce no diagnostics to help figure
out what went wrong. They were written before is_deeply() existed
because I couldn't figure out how to display a useful diff of two
arbitrary data structures.

Extending and Embedding Test::More

Sometimes the Test::More interface isn't quite enough. Fortunately,
Test::More is built on top of Test::Builder which provides a single,
unified backend for any test library to use. This means two test
libraries which both use Test::Builder can be used together in the
same program.

If you simply want to do a little tweaking of how the tests behave,
you can access the underlying Test::Builder object like so:

Returns the Test::Builder object underlying Test::More for you to play
with.

EXIT CODES

If all your tests passed, Test::Builder will exit with zero (which is
normal). If anything failed it will exit with how many failed. If
you run less (or more) tests than you planned, the missing (or extras)
will be considered failures. If no tests were ever run Test::Builder
will throw a warning and exit with 255. If the test died, even after
having successfully completed all its tests, it will still be
considered a failure and will exit with 255.

So the exit codes are...

0 all tests successful

255 test died or all passed but wrong # of tests run

any other number how many failed (including missing or extras)

If you fail more than 254 tests, it will be reported as 254.

NOTE This behavior may go away in future versions.

CAVEATS and NOTES

Backwards compatibility

Test::More works with Perls as old as 5.6.0.

utf8 / "Wide character in print"

If you use utf8 or other non-ASCII characters with Test::More you
might get a "Wide character in print" warning. Using binmodeSTDOUT,":utf8"
will not fix it. Test::Builder (which powers
Test::More) duplicates STDOUT and STDERR. So any changes to them,
including changing their output disciplines, will not be seem by
Test::More.

The work around is to change the filehandles used by Test::Builder
directly.

String overloaded objects are compared as strings (or in cmp_ok()'s
case, strings or numbers as appropriate to the comparison op). This
prevents Test::More from piercing an object's interface allowing
better blackbox testing. So if a function starts returning overloaded
objects instead of bare strings your tests won't notice the
difference. This is good.

However, it does mean that functions like is_deeply() cannot be used to
test the internals of string overloaded objects. In this case I would
suggest Test::Deep which contains more flexible testing functions for
complex data structures.

Threads

Test::More will only be aware of threads if "use threads" has been done
before Test::More is loaded. This is ok:

no_plan, todo and done_testing() depend on new Test::Harness features
and fixes. If you're going to distribute tests that use no_plan or
todo your end-users will have to upgrade Test::Harness to the latest
one on CPAN. If you avoid no_plan and TODO tests, the stock
Test::Harness will work fine.

Installing Test::More should also upgrade Test::Harness.

HISTORY

This is a case of convergent evolution with Joshua Pritikin's Test
module. I was largely unaware of its existence when I'd first
written my own ok() routines. This module exists because I can't
figure out how to easily wedge test names into Test's interface (along
with a few other problems).

The goal here is to have a testing utility that's simple to learn,
quick to use and difficult to trip yourself up with while still
providing more flexibility than the existing Test.pm. As such, the
names of the most common routines are kept tiny, special cases and
magic side-effects are kept to a minimum. WYSIWYG.

SEE ALSO

Test::Simple if all this confuses you and you just want to write
some tests. You can upgrade to Test::More later (it's forward
compatible).

Test::Harness is the test runner and output interpreter for Perl.
It's the thing that powers maketest
and where the prove
utility
comes from.

Test::Legacy tests written with Test.pm, the original testing
module, do not play well with other testing libraries. Test::Legacy
emulates the Test.pm interface and does play well with others.

Test::Differences for more ways to test complex data structures.
And it plays well with Test::More.